CERN Accelerating science

EuPRAXIA baseline parameters established
by Dr. Ricardo Torres (University of Liverpool)

Photograph of the participants at the 1st Yearly Meeting of EuPRAXIA
(Image:Copyright Pieyre Sylvaine, LLR)

The First Yearly Meeting of the EuPRAXIA consortium took place at the École Polytechnique in Paris, over 26-28th October. Ralph Assmann, Project Coordinator, and Arnd Specka, Deputy Project Coordinator and Host of the meeting, welcomed 59 registered participants from partner institutes, associate partners, and industry.

The Yearly Meeting discussed the fruitful first year of the project, which included the forming of the collaboration board, hiring of new personnel, investigation of facility parameters and a total of eleven workshops and special work package meetings. Scientific results from these events covering all aspects of the project were reported, and included interesting new insights and future directions.

One of the highlights of the meeting was the presentation and approval of the preliminary study concept of EuPRAXIA. The report summarized the scientific input for the preliminary study concept of EuPRAXIA which has been received over the past year. All work packages contributed to this report with summary reports of topical workshops held during 2016.

One such workshop was the European Plasma Accelerator meeting held in Pisa in June 2016, where more than 120 scientists gathered and discussed the various technical approaches and requirements for the collaboration over three days. Another workshop on laser technology which lead to the 100-cube laser challenge (100J / 100fs / 100Hz) has become one of the baseline components of the EuPRAXIA design.

The preliminary study concept report presents the outcome of all these discussions, condensed into flow diagrams and technical tables. The graphical diagrams show the main concepts, their interplay and the connections to relevant applications. Included in the report are the agreed baseline parameters, the parameter ranges to be explored and the technical goals for the next step of the EuPRAXIA conceptual design work.

The values of the parameters were first derived from scaling laws and refined by simulations. The parameter ranges documented in the report will ensure that work done in different locations by the project partners will be focused on the same targets and operating under the same assumptions. This common baseline for parameters and their study range will also ensure that results can be compared for beam quality, tolerances, layout footprints and costs.

At this stage, the study will contemplate multiple paths for obtaining high-quality multi-GeV electron beams. Such concepts considered include: Laser Wakefield Acceleration (LWFA) with internal or external injection and direct or staged acceleration to 5 GeV; beam-driven Plasma Wakefield Acceleration (PWFA) to 1 GeV or 5 GeV; and a hybrid scheme including LWFA and staging using PWFA to a multi-GeV electron beam.

By keeping these common baseline parameters and goals in mind, the work packages of EuPRAXIA can further investigate the techniques and approaches required.

In addition, the report contained the requirements for the plasma-based accelerator and its experimental user areas tailored for the two main applications foreseen by EuPRAXIA. Firstly, High Energy Physics and other pilot applications, and secondly, a Free Electron Laser (FEL) for ultrafast photon science.

The values for the FEL requirements were determined during several workshops held over the last six months. The requirements for the HEP applications in terms of beam parameters and infrastructure were defined by the participants of a workshop on Pilot Applications of Electron Plasma Accelerators (PAEPA) in mid-October 2016.

In the next phase of the project, the technical work will use the parameters from the preliminary study to provide a more refined table of parameters for incoming and outgoing beam and laser properties, realistic estimates of performance, basic values for tolerances and stability requirements, basic layouts (footprints) of the technical components, and a further iteration of specifications for the science applications.

The future outcome from the work packages could be used to rank the various solutions towards the final proposal, due in 2019. This ranking will define the optimal combination of technologies for the conceptual design of a EuPRAXIA facility.